The HFT4 frost protection thermostat will ensure that the heating is switched on whenever potential frost conditions are detected.  When sited in the most vulnerable part of the home, it will make sure that the temperature does not drop to the level at which frost may develop.

HFT4 has an internal temperature setting dial, so its exterior is uncluttered and unobtrusive. It uses load compensation algorithms that help save energy, while maintaining a consistent temperature (typically within ±0.5 °C).

The temperature control accuracy and the range of load compensation settings (for gas, oil and electric systems) reduce the temperature swings that occur with traditional thermostats. HFT4 helps save energy, as the control algorithm allows the boiler to operate in condensing mode for longer periods. 



  • Frost and condensation protection in sensitive areas

    The SFT020 frost protection thermostat can be fitted either standalone, or alongside a normal thermostat, in order to protect a sensitive area from low temperatures that could cause freezing or condensation. The hidden temperature setting dial (on the back of the device) enables an absolute minimum temperature to be set for a heating system, which can then override the main thermostat in the case of very low ambient temperatures.

    Control of most mains-operated heating systems

    HFT4 is perfect for controlling most mains-operated domestic gas or oil-fired central heating and hot water systems. It can save around 10% in energy costs through use of load compensation software, which optimises the switching of the boiler to maximise its efficiency.

  • Key features

    • Mains operation
      • No batteries required
      • Can connect to existing thermostat  wiring
    • Sophisticated time proportional integral (TPI) algorithm
      • Improves energy efficiency
      • Consistent and accurate control, while minimising temperature overshoot
    • Temperature setting range 0 °C to +20 °C
    • Heating ‘ON’ indicator light


    • Specification
    • What's in the box
    • Electrical

      Contact type


      Contact rating

      3 (1) A, 230 V AC, 50 Hz


      230 V AC, 50 Hz


      Set temperature

      0 °C to +20 °C

      Temperature accuracy

      ±0.5 °C



      EN 60730-2-9


      Dimensions (W x H x D)

      86 mm x 86 mm x 36 mm


      0.2 kg (approx.)


      Flame-retardant thermoplastic


      Industry standard wall plate


      Ingress protection

      IP 30

      Insulation class

      Double insulated

      Operating temperature

      0 °C to +40 °C

      Pollution degree


      • HFT4 thermostat
      • Standard 6-pin wall plate
      • User and installation guide
      • ErP Directive Class Declaration sheet